Re: Some new SPI functions - Mailing list pgsql-patches

> Who did you think would do it?
>
> regards, tom lane
>
you :-)

Seriously, I didn't give it much though. This is undoubtedly the best way
although some projects handle it differently. A  tech-writer perhaps, with
better writing skills then programmers in general. But people like that are
probabaly not too common in the open source field. If you don't do like
JBoss and charge for the docs (I'm *not* in favor of that).

Anyway, here's the patch again. This time with documentation.

Index: doc/src/sgml/spi.sgml
===================================================================
retrieving revision 1.30
diff -u -r1.30 spi.sgml
--- doc/src/sgml/spi.sgml 1 Dec 2003 22:07:57 -0000 1.30
+++ doc/src/sgml/spi.sgml 15 Feb 2004 13:47:13 -0000
@@ -573,6 +573,190 @@

 <!-- *********************************************** -->

+<refentry id="spi-spi-getargcount">
+ <refmeta>
+  <refentrytitle>SPI_getargcount</refentrytitle>
+ </refmeta>
+
+ <refnamediv>
+  <refname>SPI_getargcount</refname>
+  <refpurpose>returns the number of arguments needed when executing a plan
+  prepared by <function>SPI_prepare</function></refpurpose>
+ </refnamediv>
+
+ <indexterm><primary>SPI_getargcount</primary></indexterm>
+
+ <refsynopsisdiv>
+<synopsis>
+int SPI_getargcount(void * <parameter>plan</parameter>)
+</synopsis>
+ </refsynopsisdiv>
+
+ <refsect1>
+  <title>Description</title>
+
+  <para>
+   <function>SPI_getargcount</function> returns the number of arguments
needed
+   when executing a plan prepared by <function>SPI_prepare</function>.
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>Arguments</title>
+
+  <variablelist>
+   <varlistentry>
+    <term><literal>void * <parameter>plan</parameter></literal></term>
+    <listitem>
+     <para>
+      execution plan (returned by <function>SPI_prepare</function>)
+     </para>
+    </listitem>
+   </varlistentry>
+  </variablelist>
+ </refsect1>
+
+ <refsect1>
+  <title>Return Value</title>
+  <para>
+    The expected argument count for the <parameter>plan</parameter> or
+    <symbol>SPI_ERROR_ARGUMENT</symbol> if the <parameter>plan
+    </parameter> is <symbol>NULL</symbol>
+  </para>
+ </refsect1>
+</refentry>
+
+<!-- *********************************************** -->
+
+<refentry id="spi-spi-getargtypeid">
+ <refmeta>
+  <refentrytitle>SPI_getargtypeid</refentrytitle>
+ </refmeta>
+
+ <refnamediv>
+  <refname>SPI_getargtypeid</refname>
+  <refpurpose>returns the expected typeid for the specified argument when
+  executing a plan prepared by
<function>SPI_prepare</function></refpurpose>
+ </refnamediv>
+
+ <indexterm><primary>SPI_getargtypeid</primary></indexterm>
+
+ <refsynopsisdiv>
+<synopsis>
+Oid SPI_getargtypeid(void * <parameter>plan</parameter>, int
<parameter>argIndex</parameter>)
+</synopsis>
+ </refsynopsisdiv>
+
+ <refsect1>
+  <title>Description</title>
+
+  <para>
+   <function>SPI_getargtypeid</function> returns the Oid representing the
type
+   id for argument at <parameter>argIndex</parameter> in a plan prepared by
+   <function>SPI_prepare</function>. First argument is at index zero.
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>Arguments</title>
+
+  <variablelist>
+   <varlistentry>
+    <term><literal>void * <parameter>plan</parameter></literal></term>
+    <listitem>
+     <para>
+      execution plan (returned by <function>SPI_prepare</function>)
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><literal>int <parameter>argIndex</parameter></literal></term>
+    <listitem>
+     <para>
+      zero based index of the argument
+     </para>
+    </listitem>
+   </varlistentry>
+  </variablelist>
+ </refsect1>
+
+ <refsect1>
+  <title>Return Value</title>
+  <para>
+    The type id of the argument at the given index or <symbol>
+    SPI_ERROR_ARGUMENT</symbol> if the <parameter>plan</parameter> is
+    <symbol>NULL</symbol> or <parameter>argIndex</parameter> is less than 0
or
+    not less than the number of arguments declared for the <parameter>plan
+    </parameter>
+  </para>
+ </refsect1>
+</refentry>
+
+<!-- *********************************************** -->
+
+<refentry id="spi-spi-is_cursor_plan">
+ <refmeta>
+  <refentrytitle>SPI_is_cursor_plan</refentrytitle>
+ </refmeta>
+
+ <refnamediv>
+  <refname>SPI_is_cursor_plan</refname>
+  <refpurpose>returns <symbol>true</symbol> if a plan
+  prepared by <function>SPI_prepare</function> can be passed
+  as an argument to <function>SPI_cursor_open</function></refpurpose>
+ </refnamediv>
+
+ <indexterm><primary>SPI_is_cursor_plan</primary></indexterm>
+
+ <refsynopsisdiv>
+<synopsis>
+bool SPI_is_cursor_plan(void * <parameter>plan</parameter>)
+</synopsis>
+ </refsynopsisdiv>
+
+ <refsect1>
+  <title>Description</title>
+
+  <para>
+   <function>SPI_is_cursor_plan</function> returns <symbol>true</symbol>
+   if a plan prepared by <function>SPI_prepare</function> can be passed
+   as an argument to <function>SPI_cursor_open</function> and <symbol>
+   false</symbol> if that is not the case. The criteria is that the
+   <parameter>plan</parameter> represents one single command and that this
+   command is a <command>SELECT</command> without an
<command>INTO</command>
+   clause.
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>Arguments</title>
+
+  <variablelist>
+   <varlistentry>
+    <term><literal>void * <parameter>plan</parameter></literal></term>
+    <listitem>
+     <para>
+      execution plan (returned by <function>SPI_prepare</function>)
+     </para>
+    </listitem>
+   </varlistentry>
+  </variablelist>
+ </refsect1>
+
+ <refsect1>
+  <title>Return Value</title>
+  <para>
+    <symbol>true</symbol> or <symbol>false</symbol> to indicate if the
+    <parameter>plan</parameter> can produce a cursor or not, or
+    <symbol>SPI_ERROR_ARGUMENT</symbol> if the <parameter>plan</parameter>
+    is <symbol>NULL</symbol>
+  </para>
+ </refsect1>
+</refentry>
+
+<!-- *********************************************** -->
+
 <refentry id="spi-spi-execp">
  <refmeta>
   <refentrytitle>SPI_execp</refentrytitle>
Index: src/backend/executor/spi.c
===================================================================
retrieving revision 1.109
diff -u -r1.109 spi.c
--- src/backend/executor/spi.c 2 Dec 2003 19:26:47 -0000 1.109
+++ src/backend/executor/spi.c 15 Feb 2004 13:47:18 -0000
@@ -918,6 +918,65 @@
  PortalDrop(portal, false);
 }

+/*
+ * Returns the Oid representing the type id for argument at argIndex. First
+ * parameter is at index zero.
+ */
+Oid
+SPI_getargtypeid(void *plan, int argIndex)
+{
+ if (plan == NULL || argIndex < 0 || argIndex >= ((_SPI_plan*)plan)->nargs)
+ {
+  SPI_result = SPI_ERROR_ARGUMENT;
+  return InvalidOid;
+ }
+ return ((_SPI_plan *) plan)->argtypes[argIndex];
+}
+
+/*
+ * Returns the number of arguments for the prepared plan.
+ */
+int
+SPI_getargcount(void *plan)
+{
+ if (plan == NULL)
+ {
+  SPI_result = SPI_ERROR_ARGUMENT;
+  return -1;
+ }
+ return ((_SPI_plan *) plan)->nargs;
+}
+
+/*
+ * Returns true if the plan contains exactly one command
+ * and that command originates from normal SELECT (i.e.
+ * *not* a SELECT ... INTO). In essence, the result indicates
+ * if the command can be used with SPI_cursor_open
+ *
+ * Parameters
+ *    plan A plan previously prepared using SPI_prepare
+ */
+bool
+SPI_is_cursor_plan(void *plan)
+{
+ List *qtlist;
+ _SPI_plan *spiplan = (_SPI_plan *) plan;
+ if (spiplan == NULL)
+ {
+  SPI_result = SPI_ERROR_ARGUMENT;
+  return false;
+ }
+
+ qtlist = spiplan->qtlist;
+ if(length(spiplan->ptlist) == 1 && length(qtlist) == 1)
+ {
+  Query *queryTree = (Query *) lfirst((List *) lfirst(qtlist));
+  if(queryTree->commandType == CMD_SELECT && queryTree->into == NULL)
+   return true;
+ }
+ return false;
+}
+
 /* =================== private functions =================== */

 /*
Index: src/include/executor/spi.h
===================================================================
retrieving revision 1.41
diff -u -r1.41 spi.h
--- src/include/executor/spi.h 2 Dec 2003 19:26:47 -0000 1.41
+++ src/include/executor/spi.h 15 Feb 2004 13:47:32 -0000
@@ -90,6 +90,10 @@
 extern void *SPI_saveplan(void *plan);
 extern int SPI_freeplan(void *plan);

+extern Oid SPI_getargtypeid(void *plan, int argIndex);
+extern int SPI_getargcount(void *plan);
+extern bool SPI_is_cursor_plan(void *plan);
+
 extern HeapTuple SPI_copytuple(HeapTuple tuple);
 extern TupleDesc SPI_copytupledesc(TupleDesc tupdesc);
 extern TupleTableSlot *SPI_copytupleintoslot(HeapTuple tuple,